1. Field
The present invention relates to fill valves for controlling liquid level in a reservoir. More particularly the invention relates to fill valves having adaptors by which they may be simply and quickly mounted and demounted to allow for simplified installation and maintenance.
2. Description of Related Art
Fill valves function to maintain a predetermined liquid level in a reservoir, and are used widely in livestock watering troughs and toilet tanks. A typical fill valve includes an inlet adapted to be connected to a liquid supply, an outlet communicating with the reservoir, a valve for controlling flow from the inlet to the outlet, a device for detecting the level of liquid in the reservoir (such as a float or diaphragm responsive to water pressure), and means actuated by the detecting device for opening the valve when the liquid level is below a predetermined level.
In fill valves, the region including the valve seal and mating valve seating face can become fouled by dirt or debris in the water supply and it may be necessary to remove and disassemble the fill valve to clean this region. It is therefore desirable that the valve can be readily mounted and demounted and allows for good access for cleaning and maintenance.
The applicant's own prior art float-controlled fill valve has a main valve disc fixed to a diaphragm, the valve disc engaging an inlet valve seat to stop water passing from the inlet to the outlet. Opposing the inlet side of the diaphragm, a control chamber is connected by a port to the inlet side, such that when in this closed position, static water pressure acting on both sides of the diaphragm is the same. A spring biases the valve disc against the inlet valve seat to hold the valve closed. When the float falls, a pivoting arm connected thereto opens a pilot valve which vents the control chamber, such that the pressure on the inlet side overcomes the spring bias and opens the valve. The fill valve is formed from main two components, a cover (housing the pivoting arm and pilot valve) and a base (in which the inlet and outlet are provided). The diaphragm and spring are held between the base and the cover and the inlet is a protruding connector formed integrally with of the base.
Before this valve can be removed for cleaning it is necessary to turn off the water supply and disconnect and remove the hardware which mounts the valve to the reservoir. Even if the fill valve can be cleaned or repaired while mounted on the reservoir and still attached to the hardware connecting it, access to the valve and valve seat is difficult and requires the necessary tools to remove the base. When the fill valve is mounted below the water level of the reservoir, the protruding adaptor is passed through the reservoir wall and held in place with a sealing gasket and screw fitting and in such a case it is also necessary to drain the reservoir.
U.S. Pat. No. 5,842,498 describes a fill valve (with a diaphragm responsive to water pressure) mounted by the push-twist action of a bayonet joint. Water is supplied to the valve through a central passage in an adaptor which includes the female part of the bayonet joint, the male part with radially projecting tabs being formed on the valve body. The end of the passage in the adaptor is surrounded by O-rings which seal against an annular face provided on the male part.
Although the bayonet joint between the valve and the adaptor renders the valve readily mountable and dismountable, it does not avoid the difficulties of accessibility, particularly to the diaphragm of the valve and the mating sealing surfaces controlling operation of the valve itself. The need remains for the repairer to have the necessary skill and tools to disassemble the valve once it has been removed in order to access these mating sealing surfaces.
NZ Patent No. 328 862 discloses a float-controlled fill valve where the diaphragm and spring are held between a base and cover connected with a screw thread. The cover houses the pivoting arm and pilot valve and the base includes the inlet and outlet so unscrewing these two parts provides access for cleaning the mating sealing surfaces. A disadvantage of this design, however is that the screw connection is difficult to release without disconnecting the water supply to the valve. Additionally, when the base is removed, the spring, diaphragm and other components are not retained, thereby requiring skill and care to avoid loss of these parts and making reassembly of the valve after maintenance troublesome.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.